title: Parameters of the protein energy landscapes of several light-harvesting complexes probed via spectral hole growth kinetics measurements.
abstract: The parameters of barrier distributions on the protein energy landscape in the excited electronic state of the pigment/protein system have been determined by means of spectral hole burning for the lowest-energy pigments of CP43 core antenna complex and CP29 minor antenna complex of spinach Photosystem II (PS II) as well as of trimeric and monomeric LHCII complexes transiently associated with the pea Photosystem I (PS I) pool. All of these complexes exhibit sixty to several hundred times lower spectral hole burning yields as compared with molecular glassy solids previously probed by means of the hole growth kinetics measurements. Therefore, the entities (groups of atoms), which participate in conformational changes in protein, appear to be significantly larger and heavier than those in molecular glasses. No evidence of a small (∼1 cm(-1)) spectral shift tier of the spectral diffusion dynamics has been observed. Therefore, our data most likely reflect the true barrier distributions of the intact protein and not those related to the interface or surrounding host. Possible applications of the barrier distributions as well as the assignments of low-energy states of CP29 and LHCII are discussed in light of the above results.
authors.affiliation: Department of Physics, Concordia University, Montreal, Quebec, Canada.
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Herascu
authors.forename: Mehdi
authors.initials: M
authors.lastname: Najafi
authors.forename: Alexey
authors.initials: A
authors.lastname: Amunts
authors.forename: Jörg
authors.initials: J
authors.lastname: Pieper
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Irrgang
authors.forename: Rafael
authors.initials: R
authors.lastname: Picorel
authors.forename: Michael
authors.initials: M
authors.lastname: Seibert
authors.forename: Valter
authors.initials: V
authors.lastname: Zazubovich
mesh_terms: D000042:Absorption; D002734:Chlorophyll / Q000378:metabolism; D004735:Energy Transfer; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D018532:Pisum sativum / Q000201:enzymology; D045332:Photosystem II Protein Complex / Q000378:metabolism; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D013050:Spectrometry, Fluorescence; D018724:Spinacia oleracea / Q000201:enzymology
chemical_list: D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; D002734:Chlorophyll